Process of treating mineral oils with selective solvents



May 28, 1.935. H. TI BENNETT PROCESS OF TREATING MINERAL OILS WITHSELECTIVE SOLVENTS Filed June 23, 1933 TTORA/E.

Patented- May 28, 1935 UNITED STATES PROCESS OF TBEATING MINERAL OILSWITH SELECTIVE SOLVENTS Harry T. Bennett, Tulsa. Okla., assigner to Mld-Continentletroleum Corporation, Tulsa, Okla., a corporation of DelawareApplication June 23, 1933, Serial No.l 677,256'

14 Claims.' (Cl. ISB- 13) 6 application filed by me on April 21, 1932,Serial No. 606,764. Y.

Mineral oils, including petroleum oils and especially petroleumlubricating oil, contain different constituents which may be separatedfrom each other by treating the oil with a suitable selective solvent,and thereafter separating the selected fraction from the other fractionof the oil. 'I'he solvent may be recovered from the oil fractions in anysuitable manner, for example, by distilling and treating theY fractionswith steam.

Various advantages may be obtained by the use of such solvents toimprove the quality of a lubricating oil. The parailinic wax may beremoved to improve the pour point of the oil, or the naphthenic portionmay be separated from the more valuable paramnic portion to produce ahigh viscosity index lubricating oil.

I have foundethat satisfactory solvents for this kind of work usuallycontain acid, and are likely to contain a small quantity of dissolvedwater.

'I'he acid is very objectionable as it will cause corrosion .of theequipment, and if the solvent is a chlorinated solvent a substantialquantity of hydrochloric acid therein is likely to begin a corrosiveaction with the formation of ferrie chloride which then acts as acatalyst to increase the corrosion. y

Many of the desirable solvents are substantially insoluble in water.However, more or less water is soluble in these solvents depending uponthe temperature. The saturation point of the solvent increases inaccordance with increases in temperature, and at relatively lowtemperatures the saturation point of the solvent is decreased.Therefore, at a high temperature the solvent may contain a larger amountof dissolved water than at a lower temperature. If the solvent iscooled, a cloud or haze will appear, indicating that the water insolution is reduced, and that free water exists in the solvent. 'I'hetemperature at which this occurs is called the cloud point.

The temperature at which an oil is treated withv a solvent to effect aseparation of the oil into fractions is usually considerably lower thanthe temperature at which the solvent is separated from the oilfractions. The solvent will, therefore, have a high saturation point.when it is being recovered from the oil fractions. Since steam isusually employed as an aid to remove the soivenmhe solvent during its,winnen; tain a relatively large quantity wa' ter. When the recoveredsolvent is cooled antiI employed to effect a separat-ion o f'an oil intofrac` tions, the saturation or cloud point ofthe solvent is reduced andfree water may be therefrom. 'This free water will temiV to an emulsion,which will interfere with a sharp separation of the fractions of the011.', `Under such circumstances, itis diillcult to separate thedesirable fraction from the other fraction' of the oil. One of theobjects of this invention is to provide a highly efficient and effectiveprocess and apparatus for removing acid, or dissolved water,

from either new or reclaimed solvents. A

A further object is to provide a systeuiwhich will permit the removal ofacid and thelower'ing of the cloud point oi the solvent during the con..tinuous reuse of the solvent for oils into fractions.

With the foregoing and other objects in view.' the invention comprisesthe novel method, construction, combination and arrangements; oi.'

parts hereinafter more specifically shown in the accompanying drawing,which illus',- trates one form oi' the invention. However, itis to beunderstood that the invention'comprehends changes, variations andmodifications'V which come within the scope of the claims hereunto a'p-30.

pended. n

In the preferred form of the invention BB 'di-f chlorethyl ether isemployed as the selective sole'- vent, but other halogenated ethers maybe fused,

and some of the advantages of the present inven tion may be obtained inusing various other solvents including nitrobenzene, aniline, cresol,furfurol, dichlorethylene, trichlorethylene, crotonic aldehyde, etc.

To aid in describing one form of thIsinvenconductor I and passes throughthe separator 2, which may contain fullers earth, or other suitablematerial for removing acid or dissolved water from the solvent. Thesolvent may "then be transmitted through apipe 3 .toa container 4. 'I'heoil to be treated may be obtained from 50 a container 5. The oil andsolvent may be trans--A mitted through pipes 6 and l to amixer l. "I'hesolvent and oil, after being agitated in the mixer 8, are dischargedthrough a pipe 9 to aseparator I 0 where the oil separates intofractions more 55 2 aiiinicandmorenaphthenicthantheoriginal separatorIl.libewisepassesthroughapipe il leading to a still I1 provided with acondenser Il discharging'into a tank I.

Thesolventandoilinthestills i2and IIare preferably subjected todistillation under a vacuum. and a largeportion ofthe solvent will befreely vaporiaed and discharged to the condensers, without injectingsteam into the stills. However, as the distillation progresses. steam oraninertgasmaybeintroducedthroughpipes 2l and 2|. respectively, to removeapproximately all of thesolvent from the oil fractions.

Theparamnicfractionoftheoilmaybedischargedfromthestill I2 throughapipeinto the storage tank Il. The naphthenic fractionmaybetransmittedfromstill i1 throughapipe 22 to a storage tank 82.

The water and solvent discharged from the condenser i4 flow into thetankil where they maybepermittedtosettlebygravity. 'lhistank il is equippedwith a pipe 22 for the discharge of water, and a pipe 22 through whichthe recovered solvent is transmitted to return pipe 24.

The run-down tank Il is likewise provided with a pipe 21 for thedischarge of water, and a pipe 2t through which the solvent isdischarged to the return pipe 24.

The recovered solvent may be transmitted through return pipe 24 to theseparator 2, wherein dissolved water and acid formed in the solventduring its recovery in stills i2 and I1, may be removed from thesolvent.`

The recovered solvent. after being treated in the separator 2, may flowthrough pipe 2 to the solvent container 4 and thereafter be reused forsubsequent extractions of oil in the manner heretofore described.

The return pipe 24 for the solvent may be provided with a by-pass 2lwhereby solvent which is free of acid and dissolved water, may bereturned directly to the solvent container 4.

It will now be understood that the solvent is transmitted in an endlesscourse including the solvent container 4, the separating stationincluding the separator il, the solvent-recovery station includingstills I2 and il, the return pipe 24leading to the separator 2, orthrough the bypass 25, and thence to the solvent container 4.

- The separator 2 will remove acid and objectionable water from the newsolvent and also from the recovered solvent. The system may,

therefore, be continuously 4operated without danger of corrosion fromthe acid, and thesolvent with the objectionable water removed, willprovidev the desired sharp separation between the oil fractions inseparator il.

As a specific example of one method of carrying out this invention, Iwill state that a chlorinated solvent, such 'as BB' dichlorethyl ether,may be employed to separate a Mld-Continent lubricating oil stock intofractions more paraiiinic and more naphthenic than the original oil,while. -the `objectionable acid and dissolved water are eliminated fromthe solvent before the latter reachestheoiltobetreated.'

BB' dichlorethyl ether containing .03 per cent hydrochloric acid andhaving a cloud point 0i About two parts of BB .dichlorethyl ether andonepartoilmaybeagitatedinthemixerl and allowed to settle into layers inthe separator i0 at a temperature from 80 to 105' F. Since the cloudpoint of the solvent is considerably below the settling temperature.' asharp separation of the oil fractions is obtained. 'Ihe BB' dichlorethylether will not free any water which might cause an emulsion with the oiland prevent a sharp separation.

The material discharged from the separator Il through pipe il will be ahigh viscosity index lubricating oil, more paraillnic than the originaloil; and the material discharged through pipe il will be more naphthenicthan the original oil.

The temperature in the vacuum stills I2 and i'I-may be about 280 F.during the nrst part of the run, and it may be desirable to thereafterincrease this temperature to about 330 l". while introducing live steamthrough pipes 24 and 2i. The free water may be removed from the BBdichlorethyl ether in tanks i! and il, and the BB' dichlorethyl ethertransmitted through the return pipe 24 to the separator 2, so as toremove any acid and objectionable dissolved water formed in the BBdichlorethyl ether during its recovery in stills I2 and i1. 'Ihereconditioned BB dichlorethyl ether may then be returned by pipe 2 tothe solvent container 4 where it is ready for reuse in the extractionprocess.

To simplify the illustration, I have shown a single separating chamberlil, but it is to be understood that the paraffinic fraction of the oilmay be subjected to successive mixing and separating operations, usingadditional quantities of fresh solvent; or the naphthenic solutionresulting from one separating operation may be used in preliminarymixing and separating operations, so as to removesome of the naphthenicportions from the original oil before it is subjected to the treatmentwith fresh solvent.

In actual practice, I prefer to subject the fresh oil to a preliminaryextraction, using the naphthenic solution of another extractingoperation to remove some of the naphthenic constituents of the originaloil. Thereafter, the oil from which these naphthenic constituents havebeen removed, is mixed with fresh solvent and permitted to settle, so asto remove additional naphthenic constituents from the desired paramnicoil. As a specific illustration of the results obtained from suchoperations, I will refer to the extraction of a Mld-Continentlubricating oil, having a gravity of 26.4, a flash point of 405 F., aviscosity of 255 at F., and a viscosity index of 75. This oil was mixedwith the naphthenic solution resulting from a previous extraction, andafter separating into a layer more paramnic than the original oil and alayer more naphthenic than said original oil, the .paraillnic layer wasremoved and mixed with fresh BB dichlorethyl ether, using 2% parts. ofthe ether to 1 part of the oil. After being allowed to settle, theparaillnic portion was removed and distilled to recover solventtherefrom. The resultant paraiilnic lubricating oil had a gravity of30.8,

a ash point of 425 F., a viscosity of 198 at 100 F., and a viscosityindex of 100.

The original oil was treated with sulphuric acid and clay beforesubjecting it to the extracting process. The parailinic and naphthenicproducts may be subjected to a light treatment with sulphuric acid,using about V4 to 1,/2 pound of the acid for each barrel of the oil. andtrai-eafter contacted with a suitable adsorbent, or absorbent. material,such as fullers earth, or other suitable clay. When treated in thismanner, both products are valuable lubricating oils, the greatest value.being in the high viscosity index paramnic oil, having a highresistance to sludging and carbon formation, but the low viscosity indexnaphthenic oil is quite satisfactory for use in machines that do notrequire a high viscosity index lubricant.

It is, of course, understood that suitable valves and pumps will beemployed to efficiently control the transmission of the several fluidsfrom one station to another, and a complete commercial system which maybe a counter-current system will include numerous other details notshown in the accompanying drawing. However, this drawing is merely adiagrammatical illustration of one form of the invention, and in view ofthe foregoing disclosure, such details will be apparent to those skilledin the art. Furthermore, the invention is not restricted to suchdetails, as it extends to various modifications within the scope of theterms employed in the following claims.

I claim:

l. In the art of separating mineral oil into iractions more parafilnicand more naphthenic than the original oil, the process of usingacidcontaining solvents which comprises percolating the solvent throughfullers earth to remove the acid from the solvent, thereafter treatingthe oil with said solvent to effect a separation of the oil intofractions more parafilnic `and more naphthenic than the original oil,separately distilling said fractions and treating said fractions withsteam to recover the solvent, and percolating the recovered solventthrough fullers earth to remove acid formed in the solvent during therecovery thereof.

2, In the art of separating mineral oil into fractions more parailinicand more naphthenic than the original oil, the process of using solventscontaining acid and dissolved Water which comprises contacting thesolvent with fullers earth to remove the acid from the solvent and tolower the cloud point of the solvent to a point below the temperature atwhich the oil is to be separated, treating the oil with said solvent toeffect a separation of the oil into fractions more paraiiinic and morenaphthenic than the original oil, separately dlstilling said fractionsand treating said fractions with steam to recover the solvent, andcontacting the recovered solvent with fullers earth to remove acid anddissolved water formed in the solvent during the recovery thereof.

3. In the art of separating mineral oil into fractions more parailinicand more naphthenic than the original oil, the process which comprisesremoving acid from a chlorinated solvent, treating the oil with saidchlorinated solvent to effect a. separation of the oil into fractions,and separating the chlorinated solvent from one of said fractions.

4. In the art of separating mineral oil into fractions more paraiiinicand more naphthenic than the original oil, the process which comprisesremoving hydrochloric acid from a chlorinated solvent, treating the oilwith said solvent to effect a separation of the oil into fractions,separating the solvent from said fractions. and thereafter removing thehydrochloric acid formed in said solvent during the separation of thesolvent from the oil fractions.

5. In the art of separating mineral oils into fractions, the process ofusing a chlorinated solvent containing dissolved water which compriseslowering the cloud point of the solvent to a degree below thetemperature at which the oil is to be separated, treating the oil withsaid chlorinated solvent to eifect a separation of the oil into'fractions,- and removing chlorinated solvent from said fractions.

6. In the process of repeatedly using chlorinated solvents for theseparation of mineral oil into fractions more paraflinic and morenaphthenic than the original oil, the steps which include recovering thechlorinated solvent from the separated fractions, lowering the cloudpoint o f the recovered chlorinated solvent so as to prevent aseparation of water from the solvent during another separation of an oilwith said solvent.

7. In the art of separating mineral oil into fractions more parailinicand .more naphthenic than the original oil, the process'which comprisesremoving hydrochloric acld from dichlorethyl ether, treating the oilwith said dichlorethyl ether to effect a separation of the oil intofractiom, and

separating the dichlorethyl ether from one of said fractions.

8. The process of repeatedly using dichlorethyl ether for the treatmentof mineral oil having paramnic and naphthenic constituents, whichcomprises treating the oil with the dichlorethyl ether to effect aseparation of the oil into fractions more parailinic and more naphthenicthan the original oil, distilling one of said fractions to recover thedichlorethyl ether and treating said recovered dichlorethyl ether toremove the hydrochloric acid formed therein during the distillingoperation.

9. In the art of separating mineral oil into fractions more paraiiinicand more naphthenic than the original oil, the vprocess which comprisespercolating dichlorethyl ether through fullers earth to removehydrochloric acid from the solvent, and treating the oil with saiddichlorethyl ether to effect a separation of the oil into fractions moreparaiiinic and more naphthenic than the original oil, separatelydistilling said fractions and treating said fractions with steam torecover the dichlorethyl ether. and percolating the recovereddichlorethyl ether through fullers earth to remove hydrochloric acidformed in the dichlorethyl ether during the recovery thereof.

10. In the art of separating mineral oil into fractions more paraflinicand more naphthenic than the original oil, the process which comprisestreating dichlorethyl ether to remove the dissolved water therefrom,extracting an oil with said dichlorethyl ether to effect a separation ofthe oil into said fractions, and recovering the dichlorethyl ether fromone of said fractions.

l1. In the art of separating mineral oils. the process which compriseslowering the cloud point of dichlorethyl ether to a point below thetemperature at which the oil is to be separated, treating the oil withsaid dichlorethyl ether to effect a separation of the oil intofractions, and removing the dichlorethyl ether from said fractions. 12.In the art of separating mineral oil into fractions more paraillnic andmore naphthenic than the original oil, the process which comprisesremoving hydrochloric acid and water from dichlorethyl ether treatingthe oil with said dichlorethyl ether to effect a separation of the oilinto fractions, and separating the dichlorethyl ether from one of saidfractions.

13. In the art of separating mineral oil into' fractions more paramnicand more naphthenic than the original oil, the process which comprisescontacting beta beta dichlorethyl ether with fullers earth to removehydrochloric acid from said dichlorethyl ether and to lower the cloudpoint of said dichlorethyl ether to a point below the temperature atwhich the oil is to be separated, treating the oil with saiddichlorethyl ether to effect a separation of the oil into fractions more

